The manufacture of a three-dimensional object is well known, which includes a cyclical execution of formation of a sintered layer by irradiating a powdery layer, formed on a molding table, with an optical beam (a directional energy beam such as, for example, a laser), and formation of a second sintered layer from a second powdery layer, then formed over the sintered layer so formed, by irradiating the second powdery layer with the optical beam, until the three-dimensional object of a desired size is eventually formed. It is known that during the course of formation of the three-dimensional object in the manner described above, the optical beam irradiating position is often displaced under the influence of, for example, displacement in the position of a light source with change in temperature and/or drift brought about by the temperature and humidity of an optical beam deflecting means even though the optical beam irradiating position is calibrated prior to the start of the process. Patent Document 1 discloses correction of the optical beam irradiating position to be made during the course of formation of the three-dimensional object.
Also, Patent Document 2 discloses successive execution of trimming of, and/or removal of unnecessary portions from, the surface of a laminated body made up of sintered layers laminated one above the other, during the course of formation of the three-dimensional object.    Patent Document 1: Japanese Laid-open Patent Publication No. 8-318574    Patent Document 2: Japanese Laid-open Patent Publication No. 2002-115004